Critical speed is a valid, field-testable running-intensity anchor, reliably derivable from a single test session or even remote training data
Interpretation
Galbraith et al. showed a single-day, three-distance time-trial protocol produces a highly consistent critical speed value (CV 0.4%) regardless of recovery duration between efforts, and Hunter et al. found critical speed estimated from 8 weeks of ordinary foot-pod training data didn't differ significantly from dedicated time-trial estimates. Jones et al.'s review adds an important ceiling: critical speed is a high-intensity marker sustainable for only roughly 20-30 minutes, not a threshold that can be held indefinitely, and sits a little above maximal lactate steady state rather than being synonymous with it.
Practical implication
Recommend critical speed as an accessible, no-lab-required intensity anchor for triathletes — either via a single-visit field test or derived from existing training data — but frame it explicitly as a 'hard but time-limited' target, not a sustainable threshold pace.
Sources
3 sources, independently verified.
Clarifies that maximal lactate steady state (MLSS) and critical power/speed (CP/CS) are not synonyms — MLSS typically sits a little below CP, and CP itself is sustainable for only roughly 20-30 minutes. Important framing for using CS as a training-intensity anchor: it is a high but time-limited target, not a threshold runners can hold indefinitely.
Three time trials (3600m, 2400m, 1200m) on a single day, with either 30 or 60 minutes of recovery between efforts, produced critical speed values that didn't differ by recovery duration and correlated well with treadmill-derived CS (CS coefficient of variation 0.4%). Establishes that a single-visit field protocol is a practical, reasonably precise way for a runner to estimate their own critical speed without lab access.
Critical speed estimated from habitual training foot-pod data (3.44 m/s) didn't differ significantly from dedicated time-trial-based estimates (3.42-3.76 m/s depending on protocol), though individual agreement on the associated D' parameter was limited. Supports deriving a usable CS estimate from everyday training data rather than requiring a dedicated test session — directly relevant to triathletes without separate lab access.